1. Field of the Invention
The present invention relates to an interface apparatus between two remote control systems having transmission modes different from each other, and in particular, an interface apparatus between a first remote control system of polling communication system and a second remote control system of convention system.
2. Description of the Related Art
Conventionally, there has been proposed a remote control system of polling system (hereinafter referred to as a “polling communication system”) in which a plurality of terminal units and one transmission unit are connected with each other via a signal line, and the transmission unit performs data exchange or data of transmission and receipt between the terminal units by accessing respective terminal units by using respective addresses allocated to respective terminal units by the time division multiplexing access. In such a remote control system, in order to control an action of a load in response to a switch operation, there is provided a pair of terminal units, in which one terminal unit receives binary data inputted by a switch operation (by monitoring the switch operation), and another terminal unit controls the load such as an illumination load. The transmission unit has such mapping information that the address of the terminal unit on the switch side is mapped to or corresponds to the address of terminal unit on the load side. Consequently, when the transmission units detects an operation of the terminal unit on the switch side, the transmission unit notifies the terminal unit on the load side of the switch operation. On the other hand, the terminal unit on the load side transmits information as to the action or operating of the load to the terminal unit on the switch side via the transmission unit. This leads to that the operating state of the load can be displayed on a displaying light which is provided in the terminal unit on the switch side.
Also, there has been diffused a remote control system of convention system (hereinafter referred to as a “contention communication system”) including a plurality of terminal units, in which each terminal unit includes a microcomputer for communication, the respective terminal units operate independently and separately, and the terminal units directly communicate with each other without any transmission unit. In such a remote control system, direct communication is established between a terminal unit for monitoring a switch operation and another terminal unit for controlling a load.
In the above-mentioned remote control systems, the polling communication system is currently applied mainly for controlling illumination loads, whereas the contention communication system is currently applied mainly for controlling air conditioning apparatuses. Accordingly, in the polling communication system, the terminal units have been manufactured as products with various functions for controlling illumination loads, whereas the contention communication system is expected high reliability in the field of air conditioning control.
By the way, if it is attempted to connect the polling communication system with the contention communication system, an interface apparatus is required. Some polling communication systems have a function to provide dimming control of an illumination load. Basically, however, the polling communication system controls ON/OFF operation of the illumination load. Therefore, the interface apparatus is only required to transmit the ON/OFF information between respective systems. Namely, in a system for sending the information, a contact point is turned ON/OFF through the terminal unit. On the other hand, in a system for receiving the information, the ON/OFF state of the contact point is monitored by the terminal unit. In other words, in the respective systems, there are required two terminal units includes (a) one terminal unit for transmitting information of contact output for control to a counterpart system, and (b) another terminal unit for receiving information of contact output from the counterpart system. In order to achieve bi-directional data exchange, each system requires two units and therefore total 4 terminal units are required. Normally, two terminal units are required for transmitting information from one system to another system, and additional two terminal units are required for receiving acknowledgement of operation from another system. Thus, the information exchange between systems additionally requires four terminal units.
As described above, four terminal units are required for controlling one load of a switch of one system in response to an operation of a switch in another system. With increase in the number of combinations of switches and loads, the number of terminal units remarkably increases. As a result, there will occur such a problem that the connection relationship becomes complicated.